The present invention relates to a multiple signal processing unit for utility wiring by receiver/LAN and a utility wiring system by receiver/LAN.
Herein, the receiver means equipment having a function by which a signal can be received from an input terminal. For example, the receiver includes the receiver such as a television, CATV, cable broadcasting, FM broadcasting and in-building broadcasting; and a transmitter/receiver such as a telephone, security communication equipment and an interphone. LAN means a local area network of computers. The utility wiring by receiver/LAN means the utility wiring which is used not only for the receiver but also for LAN. The multiple signal means the signal comprising a mix of signals received by the receiver such as the television and the telephone and LAN signal.
A coaxial cable or a twisted-pair cable is installed for a receiver only inside a building such as an existing office building. For example, television broadcasting, cable broadcasting, FM broadcasting or the like is received in the following manner. A common receiving antenna is installed in place. A signal received by the receiving antenna is distributed to rooms through the twisted-pair cable or the coaxial cable. The broadcasting is received by the receiver connected to a terminal of the cable in each room.
In this case, VHF, UHF, BS, SHF, CS or the like is used as a television signal. A frequency band of from 90 MHz to 1.8 GHz is sequentially used. The frequency band of from 76 MHz to 90 MHz is used for the FM broadcasting. The frequency band of from 30 MHz to 90 MHz is used for the cable broadcasting.
The coaxial cable or the twisted-pair cable is separately used so that various signals may be assigned to the cable in accordance with the frequency.
On the other hand, LAN for connecting computers in the building through a communication line installed in the building has been recently spread rapidly. LAN has standards such as Ethernet (IEEE Standard 802.3), IBM Token ring and Apple talk. Ethernet standard is the most popular of these standards of LAN. A frequency range of 5 MHz or more can be used for the transmission of LAN signal. Mainly, the frequency range of 5 MHz, 10 MHz and 20 MHz is used in general.
A wiring of the communication line for LAN is installed independently of the wiring of the cable for the television or the like. A new wiring work is required for the existing building. A problem arises: the work is not easy and extends over a long period, thereby resulting in a high cost. Another problem arises: the new wiring work is, in fact, difficult for the existing building and consequently LAN cannot be constructed.
It is very advantageous in aspects of the work operation, the construction period and the cost to be capable of using as the cable for LAN the cable for the receiver only such as the television and the cable broadcasting which is already installed in the building. In addition to the above advantage, it has another advantage: the installation of the cable for the television etc. permits the construction of LAN even in an area in which LAN cannot be, in fact, constructed.
However, this has a disadvantage as described below. Although the frequency used for the television signal or the like does not overlap with the frequency used for the LAN signal, the frequency used for the signal output from the computer is not always within a range of the frequency used for the LAN signal. Moreover, various receivers are not designed on the assumption that they are used simultaneously with the computer. As a result, the receiver and the computer do not normally operate only by connecting the computer to the cable for the receiver only such as the television, thereby causing a serious trouble.
An object of the present invention is to permit simultaneously transmitting the signal received by the receiver such as the television and the cable broadcasting and the LAN signal through a single cable without causing interference between the signals, thereby to enable LAN to be constructed by means of cables for the television and the cable broadcasting installed in a building.
The above object is achieved by the present invention: a unit for processing a multiple signal transmitted through utility wiring by receiver/LAN, which comprises a pair of utility wiring connecting terminals connected with each other for connecting to the utility wiring; at least one input-output terminal for connecting a computer, the input-output terminal being connected to the utility wiring connecting terminals; at least one input-output terminal for connecting the receiver, the input-output terminal being connected to the utility wiring connecting terminals; and a first signal interference preventing circuit for preventing a reverse flow of LAN signal, the circuit being connected between the utility wiring connecting terminals and each input-output terminal for connecting the receiver.
Preferably, the unit comprises a second signal interference preventing circuit for preventing an interference of the LAN signal output from the computer, the circuit being connected between the utility wiring connecting terminals and each input-output terminal for connecting the computer.
Preferably, the first signal interference preventing circuit comprises a high-pass filter having a cut-off frequency which is within a range of from 76 MHz to 10 MHz. Alternatively, the first signal interference preventing circuit comprises a diode or a capacitor. Preferably, the second signal interference preventing circuit comprises a low-pass filter having a cut-off frequency which is within a range of from 70 MHz to 10 MHz.
Preferably, the input-output terminal for connecting the computer comprises any one of T-type, 2-type, 5-type and F-type Ethernet connectors or a combination of these connectors.
The above object is achieved by the present invention: a utility wiring system by receiver/LAN, which comprises a utility wiring by receiver/LAN; at least one booster located in the utility wiring, for amplifying a signal received by the receiver; a bypass circuit connected in parallel to the booster; a LAN signal pass circuit disposed in the bypass circuit, for passing LAN signal therethrough but cutting off the signal which is within a frequency range outside the frequency range of the LAN signal; and a plurality of units connected to the utility wiring, for processing a multiple signal transmitted through the utility wiring, wherein each of a plurality of units further comprises a pair of utility wiring connecting terminals connected with each other for connecting to the utility wiring; at least one input-output terminal for connecting a computer, the input-output terminal being connected to the utility wiring connecting terminals; at least one input-output terminal for connecting the receiver, the input-output terminal being connected to the utility wiring connecting terminals; and a first signal interference preventing circuit for preventing a reverse flow of the LAN signal, the circuit being connected between the utility wiring connecting terminals and each input-output terminal for connecting the receiver.
Preferably, in the system, the LAN signal pass circuit comprises a low-pass filter having a cut-off frequency which is within a range of from 50 MHz to 20 MHz.
Preferably, the unit comprises a second signal interference preventing circuit for preventing an interference of the LAN signal output from the computer, the circuit being connected between the utility wiring connecting terminals and each input-output terminal for connecting the computer.
Preferably, the first signal interference preventing circuit comprises a high-pass filter having a cut-off frequency which is within a range of from 76 MHz to 10 MHz. Alternatively, the first signal interference preventing circuit comprises a diode. Preferably, the second signal interference preventing circuit comprises a low-pass filter having a cut-off frequency which is within a range of from 70 MHz to 10 MHz.